how to print result separated with comma

DECLARE @col nvarchar(MAX);

select ColumnName into #temp  from Mnblabla

--SELECT TOP 5 AcquirerId INTO #pdxterminals FROM PDXTerminals

SELECT @col = COALESCE(@col + ',', '') +  ColumnName

  FROM #temp

  DROP TABLE #temp

  PRINT @col

------------------------------------------manasha logic-------------------------------------------

declare

@x varchar(max),

@modcolnames varchar (max),

@modcolnames1 varchar (max),

@y varchar(max)=1

drop table #temp

SELECT *, ROW_NUMBER() OVER(ORDER BY ColumnName) AS Row_Number INTO #temp 

FROM MNSuperAdminMakerChecker where Code=60

set @x=(select Count(*) from MNSuperAdminMakerChecker where Code=60)

while(@y<=@x)

BEGIN

SET @modcolnames = (SELECT ColumnName from #temp WHERE Row_Number = @y)

SET @y = @y +1

SET @modcolnames1 = CONCAT(@modcolnames1 ,',',@modcolnames)

END

SELECT @modcolnames1 as 'Modified Column'